1. Field
The present disclosure relates to nanoparticles and a method of preparing the same, and more particularly, to passivated nanoparticles and a method of preparing the same.
2. Description of the Related Art
Nanoparticles are any particles having a nanoscale (e.g., a few nanometers to a few tens of nanometers and more particularly, from about 1 nm to about 99 nm) particle size, such as quantum dots, nanowires, nanoplates, and nanospheres.
A quantum dot (QD) is a semiconductor material with a crystal structure having a size of a few nanometers and which exhibits characteristics between those of a bulk semiconductor and those of a discrete molecule of the same material. Physical, chemical, and electrical properties of a quantum dot may be controlled by changing its size in the same material because of its quantum confinement effects and large surface to volume ratio. Quantum dots may be used in electronic devices, including, for example a quantum dot light-emitting device (QD LED), a QD solar cell, and a QD transistor.
When quantum dots are aggregated or fused together, the inherent characteristics of the quantum dots may be lost reduced. In order to prevent aggregation or fusion of the quantum dots, the passivation of the quantum dots is necessary. Passivation of the quantum dots may also serve to prevent a decrease in the light-emitting efficiency of the quantum dots due to the effects, such as dangling bonds on surfaces of the quantum dots and surface defects, and may prevent a degradation of optical and electrical characteristics due to the trapping of charge carriers on the surfaces thereof.
An organic ligand may be used for the passivation of the quantum dots. An organic ligand may be attached, adsorbed, or bonded to the surface of a quantum dot. However, an organic ligand bonded to the surface of the quantum dot may function as an insulating barrier layer and may therefore decrease the electrical conductivity of the quantum dot.
Alternatively, a metal chalcogenide complex (MCC) may be used for the passivation of quantum dots (see, e.g., “Colloidal Nanocrystals with Molecular Metal Chalcogenide Surface Ligands,” Science 2009, 324, 1417-1420). MCC materials have charges on their surfaces and are bonded to the surfaces of quantum dots in a solution, allowing the quantum dots to be stably maintained in a colloidal form in the solution, similar to the case of organic ligands. However, with respect to the typical passivation of quantum dots by MCC, hydrazine, which has relatively strong toxicity and explosiveness, has generally been used as the solvent. Also, MCC materials (e.g., Sn2S6, Sn2Se6, Sb2S6, Sb2Se6, In2Se4, In2Te3, Ga2Se3, ZnTe, or HgSe2) used in a typical passivation of quantum dots by MCC are all anionic.